With a slew of donors and activists now up for grabs, the leading two Republican candidates redoubled their efforts — and made personal appeals — this week to win over unaligned high-dollar and high-power GOP players in what's become largely a two-man nomination fight.

"We're at a point when the large group of undecided activists are going to choose their candidate," said Jennifer Horn, a conservative activist in New Hampshire who hasn't picked a contender. "People are starting to accept the field and accept that these are our choices. It's time to get behind someone who is a candidate, someone who is running."

Romney, who essentially has been running for president for five years, spent a chunk of the week calling fundraisers and activists anew who have long sat on the sidelines; the former Massachusetts governor hoped they would finally decide to back him. Perry, who entered the race just seven weeks ago, was working to make up quickly for lost time; the Texas governor hoped that new supporters would give his campaign a lift after a few rocky weeks.

Both proved persuasive — to a point.

Home Depot co-founder Ken Langone, a Christie backer, quickly joined Romney's team. So, too, did billionaire supermarket executive John Catsimatidis and hedge-fund giant Paul Singer. Romney was trading friendly emails with the three even as they were publicly calling for Christie to join the race. Former Republican National Committee Chairman Jim Nicholson also said he would back Romney in the wake of Christie's exit.

Romney also picked up support from two former Tim Pawlenty supporters in Florida, former Jeb Bush aides Slater Bayliss and Justin Sayfie. And he announced the backing of Jerry Carmen, a former chairman of the New Hampshire Republican Party who has deep ties in the state.

Perry successfully wooed Iowa developer and casino owner Gary Kirke, one of about a dozen Iowa Republicans who had traveled to New Jersey last May to urge Christie to run. Kirke endorsed Perry Tuesday, calling him the one with the "skills, ideas and conviction" to be the party's nominee.

The Texan also released a list of his top supporters in New Hampshire, including people who had been sitting on the sidelines. Backers include former Sen. Gordon Humphrey as well as John Stephen, the GOP gubernatorial nominee in 2010. And a Perry aide said he plans to release a list of supporters in South Carolina next week who just signed on.

It's not clear whether Romney or Perry have been more successful at courting Christie supporters, including Wall Street donors. And it's equally unclear where Palin supporters — many from the party's conservative and tea party wings — will end up. Many turned to social networks to blast her decision not to run for president but they also didn't indicate who they would back instead.

Of the two candidates, Perry may have the better shot at picking up Palin backers, given his links to evangelical voters and tea party activists. Those constituencies aren't a natural fit for Romney, a Mormon who has switched positions on issues social conservatives hold dear. To that end, Perry's central challenge is to convince social and religious conservatives to unite behind him in places like South Carolina and Iowa instead of splintering among other candidates like Rep. Michele Bachmann and former Sen. Rick Santorum.

In South Carolina, Perry's campaign has been checking in regularly with the more than fifty local tea party groups to gauge their support. And they've been in touch with the state's pastors and religious leaders. He also plans to meet with social conservatives including some pastors when he travels Saturday through northwest Iowa, the geographic center of Iowa's evangelical conservative movement.

To varying degrees, both Romney and Perry are in a race to get the stamp of approval from the GOP establishment, which hasn't fallen in line behind any one candidate as it searches for the strongest Republican to challenge President Barack Obama.

Not everyone was picking a candidate.

Christie's most dogged suitor in Iowa, energy company owner Bruce Rastetter, said he planned to take his time before deciding who he would endorse. Rastetter expects to talk with Perry, Romney and perhaps others in the coming weeks. Romney aides said they had reached out to Rastetter and were planning a conversation, either by phone or in person.

"I look forward to engaging them in a discussion on some of the issues," Rastetter said Thursday. "I want to kind of evaluate it."

The behind-the-scenes courtship of donors and activists is a laborious — but necessary — process for the candidates.

"These races take so much money and so much organization, and of course a candidate who really knows the issues — including having a real understanding of foreign affairs," said Austin Barbour, a member of Romney's fundraising team. "It just can't happen overnight."

Money is a main goal. Romney got a head start in fundraising, bringing in $18 million in his first three months of collecting; he's likely to come in below that mark for the past three months, though he most certainly will lead Perry in cash on hand given his head start. Perry's team said he raised $17 million in his first seven weeks of campaigning and had $15 million of that in cash on hand.

The courtship of new donors and grass-roots activists reached a critical phase this week because the primary calendar has been shortened, with primary voting set to begin in just three months. In the coming weeks, candidates will have to spend more and more time campaigning to meet voters instead of making phone calls or holding private meetings